1. Field of the Invention
The present invention relates to an image forming apparatus using a process kit detachably mountable thereinto, the process kit having a casing in which process means, including corona discharging means, are contained as a unit.
2. Description of the Prior Art
In general, electrophotographic type image forming systems require replacement of a photosensitive member, resupply and replacement of developer, cleaning of corona discharging wire or other adjustments and replacements after the systems have been used for a prolonged period of time. Heretofore, such maintenance has been performed by an expert serviceman.
There have been proposed new methods by which an image forming apparatus can be maintained always in good condition without the need of relying on the expert serviceman. One of these methods is such that the used process means in the system, including a corona discharger, development device, photosensitive drum and others, can be replaced singly or in combination by fresh process means. The combination of process components will be called a process kit hereinafter.
If such a process kit is simply exchanged with another one, a user can selectively use one of various process kits having different predetermined development performances and image reproducibilities in accordance with his desire of copy. For example, differently colored images can be obtained by using three process kits containing black-, red- and blue-colored developers, respectively.
Where such a process kit is used, a corona discharger is so designed that it requires no maintenance such as cleaning under its normal application before the effective life of the process kit expires. Depending on the conditions under which the process kit is used, however, it is not always ensured that the image forming apparatus can satisfactorily continue to operate without maintenance. For example, if the image forming system is used in a dusty circumstance or if a process kit is mounted into the image forming system after this process kit has been kept out of the image forming apparatus for a prolonged period of time, any external matter such as dust, dirt and others may adhere to a corona discharging wire to degrade the obtained image, even within the service life of that process kit. It is, therefore, required that the corona discharging wire in the process kit can be cleaned to maintain it clear so that images of good quality will always be obtained.